Interfacial thermal transport in combustion-dissociation process at different environments for methane hydrate

Abstract

Abstract Currently, there is a considerable lack of research on the dissociation of methane hydrate combustion at the microscopic level. In this study, ReaxFF molecular dynamics simulations were used to accurately locate the phase transition interface during methane hydrate combustion-dissociation, and the interfacial heat transport was analyzed for different oxygen-fuel ratios and different combustion atmospheres. The time evolution of interfacial heat flux, interfacial thermal resistance and combustion production is extracted, finding that different ratios of oxygen-fuel and combustion atmospheres have different degrees of influence on the combustion-decomposition of hydrate. The larger ratio of oxygen-fuel, the greater the heat flux at solid-liquid interface, and the faster the dissociation rate of hydrate. Combustion is carried out more stably at the ratio of oxygen-fuel of 0.5. The value of solid-liquid interfacial heat flux at different atmospheres is O2/CO2 > O2/CH4 > O2. During the entire decomposition, the heat flux of burning boundary is greater than the solid-liquid interface under O2/CH4 atmosphere, lasting for about 1600 fs, which is 2.3 times than the pure O2 atmosphere. The heat flux of two interfaces at O2/CO2 atmosphere is the same, and the reactivity of CO2 plays a critical role in the decomposition driving of hydrate by reaction of CO2 + H→CO + OH at high temperature. The study reveals the heat and mass transfer mechanism of the combustion-dissociation process of methane hydrate under different combustion environments, which is of theoretical guidance for the stable combustion and controlled decomposition of hydrate.